Changes in Sensory and Physico-chemical Characteristics of Tea Leaves during Aerobic Fermentation for Black Tea

Fresh tea leaves from different tea cultivars, Qianmei 419, Qianmei 502,Qianmei 601,Qianmei 809 and Fudingdabaicha were fermented in a laboratory-made aerobic fermentor to produce black tea in comparison to natural fermentation. Changes in sensory quality were recorded at 15-min intervals during the fermentation, and leaf temperature and pH were measured as well. The results showed that during the early stage of aerobic fermentation, the leaf temperature went up quickly to a level higher than that of natural fermentation. Aerobic fermentation accelerated the color alteration of tea leaves to red and facilitated the formation of characteristics aroma. During the fermentation process, the pH value of fermented tea leaves showed a downward trend under both conditions, but decreased faster under aerobic condition. The results of sensory evaluation showed that the overall quality of black tea from aerobic fermentation was as good as that from natural fermentation.